Apparatus for burning spirit and similar liquid fuels



Dec. 13, O ow ET AL APPARATUS FOR BURNING SPIRIT AND SIMILAR LIQUID FUELS Filed Dec. 26, 1963 M \1 a? ll Q t h 1 4 0 w @w A Q Q M IX I ll 1 a n w United States Patent 3,290,907 APPARATUS FOR BURNING SPIRIT AND SIMILAR LIQUID FUELS Karl ()skar Arne Boij, Vasagatan 18, Tranas, Sweden, and Bertil Karl Axel lohansson, deceased, late of Tranas, Sweden, by Ake Erik Alexander Almqvist, administrator, Dunderbacksgatan 2, Eksjo, Sweden Filed Dec. 26, 1963, Ser. No. 334,689 Claims priority, application Sweden, Dec. 31, 1%2, 14,179/62 2 Claims. (Cl. 6780) The present invention relates to apparatus for burning spirit and similar fuels and of the kind comprising a fuel container containing a fuel absorptive, usually fibrous mass and a wick in contact with the absorptive mass and adapted to transfer fuel from the absorptive mass to the fuel-combustion point.

In previously known apparatus of the kind referred to, the upper portion of the wick fixed in the fuel container serves as a burner. The wick is usually made of glass fibres or other non-combustible material and is surrounded at its burner portion by a porous fire resistant envelope of asbestos cloth or the like, whereby it can well withstand the heat from the flame. However, by and by the burner portion will be subject to malfunction caused by the pores of the protective envelope getting choked by products forming in the course of the combustion. When using spirit as the fuel, the choking products originate from the denaturating agent contained in the spirit. When using more carbonaceous fuels, the resulting cracking products may choke the pores in the burner portion. Such choking of the pores will gradually cause complete failure of the burner portion, and since this portion is integral with the remaining apparatus, it will be necessary to discard the apparatus as a whole.

This drawback has been eliminated according to the present invention by forming the burner portion as a separate member which is detachable from the remainder of the wick and includes a fuel-sucking portion which, when the burner is mounted in place, is in direct communication with the capillary system of the fixed wick. In this construction it will only be necessary to replace the burner member after the choking of the pores having become too troublesome, while the remainder of the apparatus can still be used.

The invention is applicable, with particular advantage, to combustion apparatus in which the fixed wick is annular in cross section and is slid over a tube secured to the bottom wall of the fuel container and serving as a fuel refilling tube. In this case the separate burner member may be arranged about a central tube frictionally fitting in a telescoping manner within the fixed fuel refilling tube, the separate burner member, when mounted in place, forming an upward extension of the fixed wick with its fuel-sucking portion in direct and intimate contact with the extreme end face of the fixed wick.

A further essential improvement effected in the combustion apparatus according to the present invention is related to the arrangement of the fuel-absorbent filling of the fuel-container. It has been proposed by us before to dispose between the fuel-absorbent proper and the top wall of the fuel container a layer of wood Wool or other material forming relatively large pores without any noticeable capillary action, whereby any surplus of liquid fuel supplied can collect within this relatively large-pored layer. The improvement effected according to the present invention resides in that a relatively thin fuel-absorbent layer is disposed between the top wall of the fuel container and said relatively large-pored layer, and in that the two fuel-absorbent layers are interconnected by a wick forming a narrow fuel-transferring path between the ice two absorbent layers. Any surplus of fuel collecting within the relatively large-pored layer during refilling of the apparatus will be sucked gradually by the wick upwards into the upper absorbent layer, whereby, as a rule, a short time after refilling all of the fuel supplied to the container will have become confined within the fuel-absorbent layers thereby rendering the apparatus completely spill-proof.

Further improvements according to the invention relate to a protective casing Within which the combustion apparatus proper is intended to be placed, and are concerned with the object of preventing a non-desinable misalignment of the flame by a suitable distribution and dimensioning of apertures for secondary air admission and for letting out the gases of combustion, respectively.

Further improvements carried out according to the invention will appear from the description hereinafter of one embodiment thereof by way of example, reference being had to the accompanying drawings, in which:

FIG. 1 shows in sectional elevation a combination spirit cooking and heating stove incorporating the invention;

FIG. 2 shows a horizontal section taken along line Il--Ii in FIG. 1;

FIG. 3 shows, in vertical section and on a larger scale,

the fuel container and parts associated therewith.

Referring to the drawings and particularly to FIG. 3 thereof, numeral 10 designates a closed, cylindrical fuel container of a diameter substantially larger than its height. Securely fixed in a central opening in the top wall of the container is a'supporting tube 11 adapted to have introduced through it a fuel-transferring wick being generally designated by 12. The upper end portion of tube 11 projects a substantial distance above the container top, and its bottom end portion depends into the interior of container 10 by an amount such that its end opening is disposed at about half the container height above the bottom wall of the container. Disposed centrally within the tube 11 is a narrow fuel refilling pipe 13 over which the annularly cross-sectioned wick 12 is slid. The fuel refilling pipe or supporting tube 13 is slotted at its bottom end so as to form two pairs of diametrically opposite tongues 15. The tongues 15 are bent away from each other and secured at their ends to the bottom wall of fuel container 10. Inserted between the tongues 14 is a cross-seotionally angularly bent metal strip 16 having its concave side facing downwards, thereby forming a diametrically extending fuel distributing channel 17 between said strip and the container bottom. Centrally between its ends, the strip member 16 is curved slightly upwards, thereby establishing open communication between the fuel supply pipe 13 and the channel 17 beneath the strip member. The strip member is urged against the container bottom by the two tongues 15 of the pipe.

The fuel container 10 is filled up to slightly more than half its height with a mass 18 capable of absorbing and tively, is generally so chosen as to form a system of capillary passages capable of taking up and retaining within it a maximum quantity of liquid fuel.

The space immediately above the absorptive mass 18 is filled with a mass 19 producing relatively large intercommunicating voids, such as wood wool or the like, whereby this mass will only exhibit a limited capability of absorbing and retaining liquid fuel. On the other hand, the pores of the filter mass 19 must be sufficiently small to preclude any danger of ignition of any explosive gases collected within these pores. The portion of the container containing the large-pored filler mass 19 is intended to serve as a reserve space for receiving any liquid fuel which the absorptive mass 18 cannot retain if the broad container 10 is placed on its edge. As the container 10 is again placed in its right position, the fuel in the voids of the wood wool filling with return into the absorptive mass and will be absorbed by the latter. Thus the apparatus shown is completely spill-proof.

Disposed between the top wall of the fuel container 10 and the large-pored filling 19 is a filling 20 of a nature substantially the same as that of the filling 18. The two fillings 18 and 20 communicate with each other through a wick 21 consisting of fine glass fibres or the like andlaid about the outer edge of the large-pored filling 19. Any surplus of liquid fuel collecting within the large-pored filling 19 will gradually be sucked by the wick 21 upwards into the topmost absorptive layer 20, whereby normally all the fuel will be absorbed within the capillaries of the fillings 18 and 20.

The sucking portion 22 of the wick 12, i.e. the wick proper, is made of synthetic fibres, such as glass fibres or nylon fibres, for example. The wick 12 is extended to the very bottom wall of the container 10 through a hole cut in the absorbent disc 18, the wick being in intimate contact with the walls of said hole so that the capillary system of the wick is in communication with the system of capillaries within the absorptive mass. To obtain an increased contact surface area between the wick and the absorptive mass, the Wick may be substantially conically flared out at its bottom end, as indicated in the drawing. The portion of the wick 12 disposed within the supporting tube 13, as well as the portion thereof projecting below the latter, is surrounded by a sleeve 23 of a porous fire-resistant material, such as asbestos cloth, for example.

The glass fibres of the wick 12 are substantially finer than the fibres of the absorptive mass 18, their average coarseness being only 0.001 to 0.002 mm., for example. This means that, for substantially equal degrees of compaction of the wick and of the absorptive mass, the capillaries of the wick are, on an average, substantially finer than the capillaries of the absorptive mass. Therefore, the capillary forces in the wick will be much greater than the capillary forces of the absorptive mass, whereby the wick will keep saturated with fuel even after the major portion of the fuel originally absorbed by the absorptive mass has become consumed. This, in turn, will result in that the burner will operate with a substantially constant flame almost until all the fuel has been consumed, whereas, if the fibre coarseness, or capillary fineness, respectively, of the wick and absorptive mass were substantially equal, the fuel concentration in the wick would decrease simultaneously with the fuel concentration in the absorptive mass, resulting in a continuously decreasing flame.

As shown in FIG. 3, the fuel-transferring fixed wick 12 terminates flush with the top ends of the outer and inner supporting tubes or pipes 11 and 13. From the extreme end face of the wick 12 the fuel is sucked further upwards into the burner head 24 which is formed as a separate, detachable unit.

The burner head 24 includes a narrow tube 25 axially slotted at its bottom end and frictionally fitted telescopically within the fixed fuel refilling pipe 13. Disposed between the tube 25 and an outer tube 26, which is perforated in its upper portion, is a wick extension constituted by an inner sucking portion 27 made of fine glass fibres or the like, and an outer sleeve 28 made of a porous heat resistant material, such as asbestos cloth. The tube 26 is formed at its upper end with lugs 29 which are bent in over the wick extension 27, 28, and the tube 25 at its upper ends has lugs 30 which are bent out over the lugs 29 of the perforated tube, this assembly thus forming a burner unit which is detachable from the fixed wick. When the burner unit 24 is mounted in place, as shown in FIG. 3, the glass-wool core 27 is in direct contact with the end face of the fuel-transferring fixed wick core 22, whereby direct communication is established between the two capillary systems. The glass-fibre filling 2'7, therefore, will always suck up fuel from the fixed wick 22.

When the burner head is pushed down in place, the perforated metal tube 26 will have its non-perforate extension telescopically engaging the outer supporting tube 11. This is possible because the outer diameter of the fixed wick 12 is slightly smaller than the inner diameter of the supporting tube. The annular clearance formed between the wick 12 and the outer supporting tube 11 communicates at its bottom end with an air space formed by a piece of wire gauze 31 which is wound about the outer supporting tube 11 in the interior of the fuel container. This will result in a narrow vent passage through which air displaced from the interior of the absorptive mass during refilling of the fuel container can escape to the ambient atmosphere without any objectionable resistance.

To enable regulation of the flame size, a sleeve 32 is slid telescopically over the supporting tube 11 and is axially displaceable along the latter by means of a control mechanism. The latter, in the embodiment shown, comprises a fork 33 which is pivotally connected to the top wall of the container at 34 and alapted to cooperate with a pair of lugs 35 secured to the control sleeve 32. At its end remote from the pivot 34, the fork 33 is formed with a horizontally extending slot 36 engaged by a crank pin 37 of a crank secured to a control knob 33 which is rotatably mounted in a bracket 40 projecting upwards from the container top.

According to the drawings, the apparatus described for burning liquid fuel is intended to serve as the source of heat for a combination cooking and heating stove. The combustion apparatus is disposed on the bottom wall of a cylindrical casing 42 within which the fuel container 10 is fixed in a central position by four leaf springs 43 secured to the inner wall surface of the casing. At a higher level the casing wall has a plurality of cut-out and bent-in lugs or shoulder 44 which support a sheet-metal plate 45 formed with a wide central opening 46 through which the burner head 24 projects upwards. The plate 45 is adapted to shield the fuel container 10 against heat radiation from the flame and to direct the combustion air admitted at this low level towards the annular clearance between the control sleeve and the edge of said openlng. Supported on the plate 45 is a flame distributor shaped as an inverted cup 47. The bottom of the cup has a fiat central portion and a conical edge portion. Formed in the latter portion are a plurality of circumferentially spaced flame exit orifice 47a. Formed in said flat portion are four radially extending inward embossments 48. These embossments will be engaged by the control sleeve 32 slightly before it reaches its upper limit position upon extinguishing the flame, so that, in the extreme upper end position, or extinguishing position, the flame distributor 47 will be raised slightly from the plate 45. The embossments 48 ensure that there will always remain between the control sleeve 32 and the bottom of the cup a narrow passageway through which gases forming after the flame has been extinguished can escape freely to the ambient atmosphere. The flame distributor cup 47 is maintained in a centered position by four vanes 49 secured to the plate 45 by screws and on which a cookmg vessel, a grill or the like can be placed. The protectlve casing or can 42, being of sufficient height to shield a cooking vessel placed on the vanes 49 against the wind, has for-med in its lower portion a plurality of draught apertures 51. A circumferential row of draught aper tures 52 may be formed in the upper portion of the casing wall.

When the apparatus is to be used as a heating stove, a cover 53 is placed on the casing, this cover being provided in its depending wall portion with a plurality of circumferentially spaced outlet opening 54 for the gases of combustion and for the heated air. In addition, the fiat top portion of the cover may be provided with openings 55. For transportation purposes, the cover 53 may be placed on the stove in an inverted position, as indicated in broken lines, thereby reducing the height of the apparatus.

It should be understood that the invention is not restricted to the embodiment described in detail hereinbefore and as illustrated in the drawings. For example, it is not essential that the fuel-sucking filling within the detachable burner portion is identical in every respect with the nature of the fuel-transferring fixed wick, However, the capillary activity of the fuel-sucking portion should not be appreciately inferior to that of the fixed wick. Further modifications are also conceivable without departing from the scope of the invention.

What we claim is:

1. Apparatus for burning spirit or similar fuel, comprising a fuel container containing a fuel absorptive usually porous mass and a wick in contact with the absorptive mass and adapted to transfer fuel from the absorptive mass to the point of combustion, in which there is disposed within the fuel container a lower fuel absorptive filling layer and superposed thereon a filling layer having relatively large pores, and between the large-pared filling layer and the top Wall of the fuel container a second fuel absorptive layer, the said second fuel absorptive layer communicating through a wick with the bottom layer of fuel absorptive material.

2. Apparatus as claimed in claim 1 and comprising a flame distributor and an axially displaceable flame extinguishing sleeve, characterized in that a flame distributor in the form of an inverted cup provided with flame exit apertures is formed with radially extending depressions or embossments adapted to be engaged by the top edge of the flame extinguishing sleeve in its flame extinguishing posi tion.

References Cited by the Examiner UNITED STATES PATENTS 58,481 10/1866 Riedel 6755 316,481 4/1885 Pigeon 67-81 687,898 12/1901 Notley 67-81 690,747 1 1902 Macfie 67-70 1,481,608 1/1924 Howard 67-70 1,604,084 10/ 1926 Stafford 15 8--96 3,042,108 7/ 1962 Boij et al 158-94 3,168,132 2/1965 Axelsson l58-94 FREDERICK L. MATTESON, JR., Primary Examiner.

ROBERT A. DUA, Examiner. 

1. APPARATUS FOR BURNING SPIRIT OR SIMILAR FUEL, COMPRISING A FUEL CONTAINER CONTAINING A FUEL ABSORPTIVE USUALLY POROUS MASS AND A WICK IN CONTACT WITH THE ABSORPTIVE MASS AND ADAPTED TO TRANSFER FUEL FROM THE ABSORPTIVE MASS TO THE POINT OF COMBUSTION, IN WHICH THERE IS DISPOSED WITHIN THE FUEL CONTAINER A LOWER FUEL ABSORPTIVE FILLING LAYER AND SUPERPOSED THEREON A FILLING LAYER HAVING RELATIVELY LARGE PORES, AND BETWEEN THE LARGE-PORED FILLING LAYER AND THE TOP WALL OF THE FUEL CONTAINER A SECOND FUEL ABSORPTIVE LAYER, THE SAID SECOND FUEL ABSORPTIVE LAYER COMMUNICATING THROUGH A WICK WITH THE BOTTOM LAYER OF FUEL ABSORPTIVE MATERIAL. 